The present invention involves a system for transmitting optical signals. More particularly, the invention relates to a system for de-multiplexing signals transmitted through optical fibers between optical signal emitters and detectors.
The use of optical fibers for optical signal transmission allows for near instantaneous communications between signal emitters and detectors. In order to increase data transmission rates, it is possible to simultaneously transmit multiple optical signals over the same optic fiber line. The signals are generated or modulated to different wavelengths and transmitted together into the optic fiber line in a process called multiplexing. As a consequence of multiplexing, a step of de-multiplexing is required to segregate the transmitted signals from one another.
Several types of devices have historically been used to de-multiplex optical signals. Physical box type filters or wafer type diffraction gratings are placed at the end of optical fibers in order to de-multiplex the signals. These devices, however, have certain limitations. The use of individual couplers for linear array waveguides require considerable time to install on the ends of individual fibers or fiber bundles. Further still, couplers can only be constructed to a certain minimum size and therefore have inherent size drawbacks. As de-multiplexing systems increase in complexity due to higher volumes of signals being carried, the physical size of an installed unit becomes larger, thus requiring additional space. The drawbacks of the prior known conventional technologies for use in fiber optics include signal losses and time in installing physical devices. It would be desirable to provide improvements to the process of de-multiplexing in order to eliminate the drawbacks with the known systems and to reduce cost.
The present invention provides an optical fiber based wavelength de-multiplexing system. The fiber based wavelength de-multiplexing system has the capability of receiving multiplexed optical signals from signal emitters and de-multiplexing them through an etched diffraction grating. The system includes an optical fiber taper with an etched diffraction grating located on the larger diameter end. The smaller diameter end of the optical fiber taper is optically connected to a transmission fiber. Optical signals, generated by an optical signal emitter, enter the transmission fiber and are transmitted through the transmission fiber to the optical fiber taper. The transmitted signals enter the smaller diameter end of the optical fiber taper and are transmitted to the larger end of the taper. The transmitted signals are de-multiplexed based on wavelength by the etched diffraction grating on the optical fiber taper.
In another aspect, the invention provides a wavelength de-multiplexing system in which optical fiber tapers are optically connected to each end of an optical fiber. The larger diameter end of each optical fiber taper has an etched diffraction grating. Optical signals generated by a signal emitter are multiplexed and transmitted through the optical fiber tapers and the transmission fiber in each direction. The optical signals are then de-multiplexed through the etched diffraction grating on the ends of the optical fiber tapers.
In another aspect, the invention also provides a method of performing bi-directional de-multiplexing. The method entails providing a first and second optical fiber taper. A transmission fiber is optically connected to the smaller diameter ends of the optical fiber tapers. The two larger diameter ends of the optical fiber taper have etched diffraction gratings located thereon. Optical signals are generated by an optical signal emitter, and are multiplexed and transmitted through the first optical fiber taper and through the length of the first optical fiber taper. The multiplexed signals are then transmitted through the second taper to the etched diffraction grating. The signals are de-multiplexed by the etched diffraction grating. As a result of having two etched diffraction grating ends, signals may be de-multiplexed in either direction, allowing for bi-directional optical communication between the ends of the tapers.